In the electrical utility industry, it is common to use detachable or socket type watthour meter assemblies to measure the electrical power consumption of a residence or a commercial establishment. Often, for various purposes, it is desired to provide an adaptor between the meter socket and the meter. A function of one type of adaptor is to disconnect the electrical service to the residence or commercial establishment. When electrical service is to be disconnected, it is usually desirable that the meter be left in the assembly for future service reconnection.
Various devices have been used for this purpose. Internal switches have been found too costly. Plastic sleeves have sometimes been placed over the meter contact blades, and the meter re-inserted into the meter socket; however, this method leaves no visual indication that the meter is disconnected. Another method has involved the use of a pair of plastic adaptors having rearwardly extending plastic blades for insertion into the meter socket jaws, and forwardly facing slots, radially spaced from the plastic blades for receiving the meter contact blades, so that the contact blades of the assembled meter are insulated from the meter socket jaw contacts, and the meter is disposed at an angle to its normal position, giving visual indication that the meter is not connected. Such a device is shown in U.S. Pat. No. 3,614,708 issued Oct. 19, 1971.
However, such devices have found only limited usage, because of the fact that they cannot be used with all types of meters. In some types of meter sockets, the rotation of the meter required by the adaptor causes mechanical interference between portions of the meter and portions of the socket. In other types of sockets the presence of terminal supporting crossbars prevents assembly of the adaptors into the socket contacts.
Other functions of meter adaptors are to allow the use of 3 wire meters on 2 wire sockets and vice versa, for connecting recording voltmeters, or to provide internal switching devices for controlling the power to the circuits.